For years, Benjamin Netanyahu’s opponents warned that Israel would eventually face a “diplomatic tsunami” for failing to resolve its conflict with the Palestinians. That threat couldn’t have been more real or more imposing as the Israeli prime minister took the podium on Friday at the United Nations in New York.

Over the past week, Australia, Britain, Canada, France and Portugal, expressing outrage over Israel’s conduct of the Gaza war, had all said they recognized a Palestinian state, a landmark step that Israel never wanted to see them take and that the Trump administration had tried but failed to forestall.

And a week before that, on the fifth anniversary of the Abraham Accords, Israel’s Arab partners in those pacts gathered not to celebrate the milestone but instead to denounce Israel, over its botched attempt to kill senior Hamas negotiators meeting in Doha, Qatar.

International pressure over the Gaza war, which was ignited by the Hamas-led attack on southern Israel on Oct. 7, 2023, can already be felt across Israeli life. European nations have imposed or threatened new tariffs, while arms embargoes are complicating Israel’s ability to replenish its arsenal. Its tourists are greeted by protests and harassment overseas, and its soccer teams face a possible suspension from international play.

Yet the Israeli leader knows that he has President Trump in his corner. And it was not a chastened Mr. Netanyahu but a defiant one who addressed the General Assembly, or at least the few delegates who stayed to hear him out after scores of others walked out in protest.

He shamed countries whose support for Israel after the Oct. 7, 2023, massacre, he said, “buckled under the pressure of a biased media, radical Islamist constituencies and antisemitic mobs.”

“When the going got tough,” he added, “you caved.”

He railed against countries using economic, political or legal measures against the Jewish state, saying such moves were an indictment not of Israel but of “weak-kneed leaders who appease evil rather than support a nation whose brave soldiers guard you from the barbarians at the gate.”

And he said bitterly that the rush to recognize Palestinian statehood had sent the Palestinians a clear message: “Murdering Jews pays off.”

Mr. Netanyahu routinely projects defiance in his U.N. speeches, which are interpreted in Israel as aimed more at a domestic political audience than an international one, though delivered thousands of miles from home and in English, not Hebrew.

“The isolation is real, but Netanyahu calculates that his domestic political base rewards defiance more than conciliation,” said Eli Groner, a former director general of the prime minister’s office. “He’s able to use international pushback as proof to Israelis that he’s the only one who won’t bend.”